Cultural evolutionary theory is quickly gaining traction as a unifying framework for the social sciences. However, research into culture acquisition paints a picture of children as vessels for inheriting evolved culture from adults, rather than cultural producers in their own right. ChACE aims to overturn this long-established orthodoxy by taking child and adolescent peer cultures as a focal point. Neglected by cultural evolutionary theorists, peer cultures are incredibly well conserved across generations despite threats to social transmission inexistent in adult cultures, challenging our understanding of how cultures are maintained and changed across generations. By intensively studying children’s peer cultures, ChACE thus stands to discover novel causal mechanisms for cultural evolution. ChACE specifically advances two ground-breaking hypotheses built upon firm theoretical and empirical foundations in folklore, cultural evolution, human life history, and cognitive development: (1) Peer cultures evidence distinct cultural evolutionary mechanisms from adult cultures; (2) Knowledge produced as part of peer cultures helps communities adapt to social and ecological change. ChACE will develop a robust and transferable methodology to jumpstart the study of peer cultures. Reflecting best-practice workflows for causal analysis, ChACE will first build ethnographically informed agent-based models to derive testable and falsifiable predictions. These will be empirically evaluated via experiments, observations, surveys, and interviews with children and adolescents aged 4-16 years, and their caregivers, at four globally representative field sites undergoing rapid culture change: the Likouala (Republic of the Congo), the Omo Valley (Ethiopia), Toledo (Belize), and County Durham (U.K.). In doing so, ChACE will initiate a disciplinary course correction by driving forward an explicit and holistic account of children’s adaptive contributions to culture change.